1. Field of the Invention
The present invention relates generally to an air mat, and more particularly to an air mat suitable for preventing decubitus that can easily afflict a bedridden patient.
2. Description of the Related Art
Decubitus is a symptom that can arise mainly in the tissues in bony areas of a bedridden patient, for example, caused by necrosis due to local oppressions of the tissue and resulting obstruction of blood circulation therein while he or she has been in bed for a long time.
If the patient does not suffer from such decubitus, he or she often feels pains or unpleasant oppression at the bony areas. In order to relieve such pains and unpleasant oppression, an air mat has been developed and widely used which consists of a multiplicity of interleaved elongate air cells arranged in parallel in the direction of the width of the air mat (hereinafter referred to as the transverse direction or the direction of the mat width). These air cells are divided into two groups such that the two groups of the air cells are inflated with air and deflated alternately at a given period of time.
We also refer to the longitudinal direction of the mat as the direction of the mat length; and the length and the width of air cells as the cell length and the cell width, respectively.
Unfortunately, such known air mat as mentioned above abuts symmetrically on the back of the patient at his right and left sides, since air cells extend linearly in the transverse direction of the mat.
It is known that given stimuli at bilaterally symmetrical positions, a patient feels the positions of stimuli clearly since a nerve net of a human being has a generally bilateral symmetry.
Further, the patient often feels inflation and deflation operations of the air mat not only monotonous but also uncomfortable when the air mat is partially deflated because then his/her body tends to sink due to his/her weight.
To solve such problems as mentioned above, an air mat has been disclosed in which each air cell is divided lengthwise into right and left sections communicating with each other at the center thereof, and arranged in such a way that the right and the left sections are offset to each other in the longitudinal direction of the air mat.
Having this structure, the air mat can support the body of the patient stretched out on the air mat, with a central groove formed along the connecting sections of the right and the left section fitting better to the patient's backbone with a less pressure.
In this type of air mat, however, the central connection sections extends along the length of the air mat and the central connection sections make a rather deep and steep longitudinal V-shaped groove as the right and the left air cells are fully inflated. Consequently, the area of the air mat supporting the backbone is reduced to a degree that part of the groove sometimes fails to abuts on the backbone. This can result in an extreme decrease in the supporting force of the air mat for the backbone.
The decrease in the supporting force acting on the backbone implies a corresponding increase in the supporting force acting on its neighboring areas, thereby failing to provide the patient with losing a comfortable uniform distribution of the supporting force on the back.
The invention is directed to overcome these problems by providing an improved air mat which can support in good balance the backbone section as well as its neighboring area of the patient, so that the patient may rest on the air mat in comfort.